After the arm is swollen from the vaccination, different treatment should be made according to different situations. If it is caused by the drug not being completely absorbed, it can be observed for a period of time and no special treatment is needed. If there is bruising in the swollen area, it is considered to be caused by subcutaneous bleeding, blood oozing or accompanied by tissue fluid exudation, you can apply cold towels or ice on the surface to effectively reduce the further expansion of edema. If the swelling is still not eliminated after 1-2, consider applying hot towels to the surface to accelerate local blood circulation, which can eliminate the bruising or inflammatory factors and inflammatory media as soon as possible, and the pain in the patient’s arm will be significantly reduced.